1. Field of the Invention
The present invention relates to an integrated-inverter electric compressor for an in-vehicle air-conditioning apparatus and to an inverter device thereof, the integrated-inverter electric compressor being formed by integrating the inverter device with the outer periphery of a housing accommodating an electric motor and a compressor.
This application is based on Japanese Patent Application No. 2008-081853, the content of which is incorporated herein by reference.
2. Description of Related Art
Recently, various electric compressors having integrated inverters have been proposed for in-vehicle air-conditioning apparatuses. These integrated-inverter electric compressors have an inverter container (inverter box) on the outer circumference of a housing accommodating an electric motor and a compressing mechanism, and an inverter device, provided inside the inverter container, that converts DC power supplied from a high-voltage power supply unit to three-phase AC power and supplies it to the electric motor via a glass sealed terminal. In this way, the rotational speed of the compressor is variably controlled according to the air-conditioning load.
As described in Japanese Unexamined Patent Applications, Publication Nos. HEI-8-322264 and 2004-162618, the inverter is integrated with the outer circumferential section of the compressor housing by providing a power-related substrate (including a platform and unit base) and a CPU substrate (printed circuit board) in two vertical layers. The power-related substrate has a plurality of power semiconductor switching devices (IGBTs) for converting DC power to three-phase AC power. The CPU substrate has a control and communication circuit having a device that operates at low voltage, such as a CPU. The substrates are mounted to the outer circumferential section of the compressor housing by accommodating them inside an external frame.
There is a need for decreasing the size of compressors of in-vehicle air-conditioning apparatuses in order to maintain the ease of mounting in highly dense engine compartments of vehicles. Even for integrated-inverter electric compressors having an integrated inverter device, there is a strong need for decreasing the size of an inverter container including the inverter devices. To fulfill such needs, the inverter device is formed as a module in order to decrease the size of the inverter device and the inverter container and to facilitate assembly.
In such a case, the inverter device is formed by mounting a CPU substrate (printed circuit board) above the power-related metal substrate of an inverter module, the inverter module being formed by integrating a power-related metal substrate on which a bare power semiconductor switching device is mounted and a resin case integrally formed by insert-molding it with a plurality of terminals, a bus bar, and so on.
However, with an inverter device having the above-described configuration, the CPU substrate may be slightly larger than the resin case and may be mounted on the upper surface of the resin case. In such a case, someone might directly touch the CPU substrate and/or hold the CPU substrate when transporting or assembling the inverter device. As a result, there is a risk that the CPU substrate might be damaged, or static electricity might be generated, thus causing damage to the CPU substrate.